The freshness of many food products is preserved by storing them in sealed containers since spoilage of food is accelerated by exposure to air, either through the effects of moisture in air or the oxidative effects of atmospheric oxygen. Food is thus commonly stored before an initial use and between uses in closed, tightly sealed containers in an effort to preserve and extend the useful life of the food by limiting the supply of air that the food is exposed to.
Various sizes and shapes of sealed containers are used to contain and store food away from the components of air which cause oxidation and moisture spoilage. These sealed containers are normally used, however, as simple closed vessels for preventing the food from being exposed to air. When food is stored in typical sealed containers, there is usually accompanying air which is trapped within the sealed container. This accompanying air can still have detrimental effects on the useful life of the enclosed food. When the container is opened to access the food stored therein, a new volume of air is trapped in the container when it is re-sealed which causes the continued deterioration of the quality of the stored food.
As such, storage containers have been developed which provide an airtight seal and which are configured to allow the evacuation of the accompanying air from the space around the enclosed food. Such containers usually include a manually operated or electrically-powered mechanism for evacuating air from the container.
Containers including a manually operated mechanism for evacuating air from an interior of a container are described, for example, in U.S. Pat. Nos. 5,558,243, 5,564,480, 5,564,581, 5,611,376, 5,692,632 and 5,803,282, all of which are incorporated by reference herein. Generally, the containers include a vacuum pump manually actuated by reciprocating a piston rod in the pump, applying external force to the body of the pump or squeezing it.
Containers including an electrically-powered mechanism for evacuating air from the interior of a container are described in U.S. Pat. No. 5,964,255, incorporated by reference herein. These containers include a vacuum pump arranged in a base and operable by battery power and a switch for supplying power to the pump when desired.
Generally, the prior art containers include a vessel defining a storage receptacle and a cover engaging with an upper lip of the vessel to enclose the receptacle. Thus, the opening of the receptacle is arranged at the top of the vessel.
It is a problem with such prior art containers that it is difficult if not impossible to store relatively large, planar food products such as cakes therein since the cakes can only be dropped into the containers through the opening at the top of the vessel. It is not possible to gently place the cake on the bottom surface of the vessel because there is insufficient room to place the cake while holding it from its bottom. Dropping the cake into the container will invariably result in damage to the cake. Thus, such containers cannot practically be used to store cakes and other large food products.